|  | 1.4 | Network Layer Functions
| 1.4.3 |
Path determination in the contexts of packets and routers
Path determination is the path traffic should take through the network cloud. Routers evaluate the best known path for traffic. Path determination occurs at Layer 3, the network layer. Routing services use network topology information when evaluating network paths. This information can be configured by the network administrator or collected through dynamic processes running in the network. The network layer connects to networks and provides best-effort end-to-end packet delivery services to its user, the transport layer. The network layer sends packets from the source network to the destination network based on the IP routing table. After the router determines which path to use, it can proceed with switching the packet. Switching involves taking the packet the router accepted on one interface and forwarding it to another interface or port that reflects the best path to the packet's destination.